1. Technical Field
The present invention relates to a meter unit used in a meter device that rotatably supports a rotation shaft which a pointer is attached, in the meter devices of various uses for a meter for a motor vehicle, a meter for a ship, a meter for an aircraft or the like.
2. Background Art
In meter devices used in various kinds of meters, a motor and a gear for transmitting torque from the motor to a rotation shaft are accommodated in a case, and the rotation shaft to which the turning force or torque from the gear is transmitted to rotate is rotatably supported relative to the case. In such a meter device, in order to suppress a minute swing movement of the rotation shaft during a rotation, frequently, a resin spring is formed integrally with the gear.
However, the resin spring is liable to generate a permanent set in fatigue due to an aged change, namely a permanent deformation. Accordingly, when the resin spring is used for a long period of time, a force for pressing the rotation shaft in an axial direction is weakened to increase the minute swing movement of the rotation shaft.
Thus, a rotation shaft support structure is proposed that can avoid the increase of a minute swing movement of a rotation shaft caused by an aged permanent set in fatigue and suppress the minute swing movement of the rotation shaft (see JP-A-2005-253272).
Specifically, as shown in FIG. 13, the rotation shaft support structure includes a case 101 including an upper case 101A and a lower case 101B and fixed to a wiring board 106. A thrust leaf spring leaf spring 102 made of a flat-plate-shaped metal is mounted between a gear 103 and the case 101 so as to be freely bent in the case 101. Accordingly, a pointer not shown in the drawing or a pointer shaft 105 to which the pointer is attached can be smoothly rotated.
In the rotation shaft support structure, as shown in FIG. 14, a rotation shaft 104 extending integrally from the pointer shaft 105 is inserted into a hole 102B (see FIG. 15) of a central part of the leaf spring 102. Further, a boss 104A fixed to the rotation shaft 104 is pressed to the leaf spring 102 to bend the leaf spring 102 in a curved state. A reaction force from the leaf spring 102 at that time is used as a load to generate a braking force to the rotation shaft 104.
Further, in such a rotation shaft support structure of the meter device, in order to take in a light from a light source from a base end part of the rotation shaft, guide the light to an end through an inner part of the rotation shaft, emit the light and illuminate a pointer attached to the end of the rotation shaft, the rotation shaft is also known that is formed with a transparent material having a good light guiding property. Such a rotation shaft support structure is called “type also serving to guide lights”.